2nd Gen Non-Engine/Transmission Cruise Control Problem??

[HBarlow]

My odometer shows almost 235,000k . . . about 99% highway miles using cruise control. About a week ago while running along at highway cruise speed I began experiencing momentary stumbles. I watched the gauges closely and soon found that when the truck stumbled I'd see the boost gauge had dropped off for a moment and was returning to normal cruise range. Soon I discovered that the stumble only occurred when using cruise control so the problem was not caused by a failing VP-44 or MAP sensor.



I knew that the cruise control recdeives speed input from the speed sensor on the differential housing so I watched the speedometer to see if it was dropping off momentarily. It was not.



I decided the problem is in the cruise control system. I have learned from another member that the cruise control in my truck is operated by a mechanical vacuum servo system not an electronic module. The TDR member suggested inspection for a vacuum leak in the lines running under the driver's side battery box and also inspecting for a wiring problem under the steering column.



Has anyone experienced a cruise control failure similar to mine? If so, what was the cure?



Harvey

 

[Joe Mc]

I had to replace the servo under the battery - it had rotted due to the close proximity to the battery acid fumes. That was about 3 years ago and all is still well. Cost for the servo was about $70. I think? Dealer had to order - took 3 days. Job is about a 2 - 3 hours in your driveway, no special tools required. Definitly check all hoses first though.

 

[HBarlow]

Joe,



Thanks for the info. I suspect that is my problem also. The chronology sounds about right also if your '99 truck's servo failed approximately three years ago it sounds reasonable that mine has failed at about the same age. I will check the vacuum hoses first as you suggested. No sense in paying $70 or more for a part if I could get lucky and find a leaking hose.



Once again TDR members have almost certainly solved a problem for me.



Harvey

 

[GAmes]

Harvey,



If you find a hole in the module under the battery you might try covering it with a 2 part epoxy. I did that to mine and got another 2 yrs of use out of it before it quit completely.



Gary

 

[HBarlow]

Gary,



Thanks for that info. I'll inspect for that before I order a servo. Oddly, on a trip north to Pendleton from the Los Angeles area my cruise control operated normally again.



I don't think I have any acid corrosion under the battery. One of the first things I always do to a new automobile (or newly installed batteries) is to apply wheel bearing grease to battery terminals. I usually monitor battery corrosion pretty closely.



Harvey